We humans like to think of ourselves as highly evolved creatures, but if we are supposedly evolution’s greatest creation, why do we have such bad knees? Why do we catch head colds so often—two hundred times more often than a dog does? How come our wrists have so many useless bones? Why is the vast majority of our genetic code pointless? And are we really supposed to swallow and breathe through the same narrow tube? Surely there’s been some kind of mistake.